火電廠專業(yè)英語

1、1. Modern electric generating stations1.現(xiàn)代發(fā)電廠1.1 how power is generated 1.1 電是如何產生的 Virtually all the electric power in the United States today is generated by one of the methods depicted schematically in fig.1.1. 事實上，今天所有的美國電力都是由圖1.1所示意的一種方法所產生的。Approximately 90% of the electric power are generated

2、 by what is called the thermal-mechanical generation concept. In this concept, heat energy is converted into mechanical energy which powers an electric generator. Most of these power plants use the Rankine cycle for conversion of heat energy to mechanical power. 接近90%的電力是通過熱機發(fā)電的理念而產生的。這個觀念認為，熱能可以轉化為

3、機械能，而機械能又可以通過發(fā)電機轉化為電能，大部分電廠使用朗克循環(huán)的方法將熱能轉化為電能Fossil-fuel plants represent the most common application of the thermal-mechanical concept. 化石燃料電廠是最典型的熱電應用Coal, gas, or a petroleum fraction is mixed with air and injected into a boiler where combustion takes place.煤、天然氣、石油與空氣混合注入到鍋爐中進行燃燒。In most plants,

4、heat from combustion is used to convert water to steam. 在大部分電廠中，燃燒產生的熱量將水轉化成水蒸氣。This steam, in turn, flows through large pipes to a multistage turbine.蒸汽流經大型的管道進入多級汽輪機中。In some plants fired by petroleum or gas, the combustion products flow directly to the turbine. 在一些燃油和燃氣火電站中，燃燒產物直接流入汽輪機中As the ste

5、am or hot gas passed through the turbine, energy is extracted from the vapor to run the turbine.當蒸汽或熱氣流經汽輪機時，蒸汽中的能量也流經汽輪機。The turbine is mechanically connected to the generator, and it drives or rotates the generator, allowing the production of electrical energy. 汽輪機和發(fā)電機在結構上相聯(lián)，它驅動發(fā)電機轉動，產生電能。1.2 Stea

6、m Power Plants1.2 蒸汽發(fā)電廠 The most widely used fossil systems burn coal or a heavy petroleum fraction to supply the thermal energy, and employ a steam turbine to power the electric generator.最廣泛應用的礦物質燃燒系統(tǒng)是燒煤或者燒油來提供熱能，利用蒸汽輪機來驅動發(fā)電機。Fossil-fuel plants represent the most common application of the thermal-

7、mechanical concept. 礦物質燃料電廠體現(xiàn)的是最普通的熱機發(fā)電的理念Coal, gas, or a petroleum fraction is mixed with air and injected into a boiler where combustion takes place. 煤、燃氣、石油夾雜在空氣中注入正在燃燒的鍋爐內。 In most plants, heat from combustion is used to convert water to steam. 在大部分電廠中，燃燒獲得的熱量用于將水轉化為蒸汽。This steam, in turn, flows

8、 through large pipes to a multistage turbine.蒸汽依次流過大型的管道，進入多級的汽輪機中 In some plants fired by petroleum or gas, the combustion products flow directly to the turbine. 以油氣為燃料的電廠其燃燒出的蒸汽直接導向汽輪機As the steam or hot gas passed through the turbine, energy is extracted from the vapor to run the turbine.當蒸汽和熱氣經過

9、汽輪機時，由蒸汽中所散發(fā)出的熱量推動汽輪機， The turbine is mechanically connected to the generator, and it drives or rotates the generator, allowing the production of electrical energy. 汽輪機與發(fā)電機由機械連接起來，由它驅動或者轉動發(fā)電機，實現(xiàn)發(fā)電。Key:HPT=high pressure turbine LPT=low-pressure turbine IPT=intermediate-pressure turbineFigure 1.2 Heat

10、 cycle for a coal-fired boiler Coal has been, and for at the next decade or so will continue to be, the largest source of fuel for electrical generating stations in the United States. 在將來十年甚至一直往后，煤都是美國發(fā)電廠最大的燃料來源As early as 1925, coal generated 57% of this countrys electrical power. 1925年，國家靠煤發(fā)電57%，

11、Coal generated an average of 52% of the electrical power during the period from 1925 to 1970. 從1925年到1970年，國家靠煤發(fā)電52%，Utilities burn about 65% of all the coal mined in the united states. 使用了占全國煤燃料的65%In 1984 it is projected that coal will generate approximately 47% of the electrical power, and 875 mi

12、llion tons of coal will be consumed.在1984年，計算出靠煤發(fā)電47 %，消耗了8.75億噸的煤。 U.S. policy is to move away from the use of petroleum for electric power generation.美國的政策是取締使用燃油發(fā)電 This de-emphasis on petroleum use for electric power generation will take years to take a substantial effect.取締燃油發(fā)電還需要過一些年才能發(fā)揮實效 Powe

13、r generation by petroleum dropped slightly in 1947-1975 as a result of the original oil embargo, but in 1976 the use of petroleum rose to an all-time high of 556 million barrels for the generation of 320 billion kilowatt-hours. 在1947年到1975年，由于原油禁運燃油發(fā)電略有下降，但是在1976年燃油發(fā)電量達到歷史最高水平，燃油5.56億桶，發(fā)電3200億千瓦時It

14、has been estimated that completion of all the petroleum-fired generating units on order during the 1970s will result in a peak use of 900 million barrels of petroleum for power generation should begin to decline thereafter.據(jù)估計，七十年代的燃油發(fā)電廠的建成，導致燃燒9億桶燃油發(fā)電的使用高峰，這個數(shù)值會在今后下降 As coal and nuclear plants assu

15、me a greater share of the base-loaded generation, oil plants will be increasingly used for peak or intermediate power production. 隨著燃煤和核電電廠占發(fā)電比例的增大，燃油電站會越來越多地用于發(fā)電的中介部分However, it is expected that utilities will continue to use substantial amounts of petroleum well into the next century.但是，有人預測，在下一個世

16、紀，燃油還會被使用相當?shù)囊徊糠?。Introduction to Power Plant Systems and Components 火電廠系統(tǒng)和部件的介紹The block diagram of Fig.1.3 show the major segments of a modern coal-fired power plant.圖1.3所示的方格的內容就是現(xiàn)代火電廠的主機設備的構成。 After crushing and pulverizing, the coal is fed to the furnace, where it is burned. 煤經過粉碎和研磨之后， 被送到爐腔中進行燃

17、燒。In the flame region, much of the heat generated is transferred to boiler tubes which line the walls. 在火焰區(qū)，大部分所產生的熱量被轉移到沿墻壁布置的鍋爐管道上。The steam water mixture formed in the boiler tubes proceeds to a steam drum, where the vapor and liquid are separated. 在鍋爐管道里的汽水混合物流入到汽包里，在這里進行水汽分離。The liquid is retur

18、ned to the boiler tubes and the vapor proceeds to a superheater. 液體流回鍋爐管道，而水蒸氣則流入過熱器。There the hot gases leaving the flame region superheat the saturated steam produced in the boiler section. 熱氣從火焰區(qū)出來，對鍋爐管道里產生的水蒸氣進行過熱。The superheated steam produced in the boiler section. The superheated steam procee

19、ds to the turbine, where its thermal energy is converted to mechanical energy. 過熱后的水蒸氣流過鍋爐，又流過汽輪機，在這里熱能被轉化為機械能。 The steam leaving the high-pressure stage of the turbine is reheated in the furnace prior to being sent to the low-pressure sections of the turbine. 蒸汽在離開汽輪機的高壓級后，在進入汽輪機低壓級之前，在爐腔中被重新加熱。The

20、 steam exiting from the low-pressure turbine proceeds to a condenser. 蒸汽離開汽輪機低壓級后，進入一個冷凝器中。The liquid from the condenser is reheated in regenerative feed-water heaters, using steam bled from the turbine, prior to being returned to the furnace. 從冷凝器中流出的液體在流回爐之前，利用從汽輪機中流出的蒸汽，在供水加熱器中再次加熱，凝汽器的凝結水在返回爐腔之前

21、，在再生式給水加熱器中利用汽輪機的抽氣進行再熱。The feed-water then proceeds to the furnace, where it is brought to near saturation in the economizer. 給水流入到爐腔中，它可以在省煤器中達到接近飽和The gases leaving the economizer preheat the entering air and are then discharged through the stack.氣體流過省煤器，使空氣提前預熱，然后釋放出來 Particulates in the gas str

22、eam are removed by electrostatic precipitators prior to discharge. In newer plants, the exit gases are also scrubbed to remove SO2.蒸汽中的微粒在被蒸汽被釋放出之前，靜電除塵器除去。在新電廠中，所釋放的氣體還要考慮脫硫。The major factor in establishing the size of the power plant components is the required net power output.所建電廠的規(guī)模由凈發(fā)電量所決定。 How

23、ever, the design is significantly affected by the characteristics of the coal being burned, coal delivery methods, combustion technique selected, and constituents of the coal ash.但是，對電廠的設計要考慮到所燃燒煤的特性，煤的運輸方法，所選擇的燃燒技術，以及煤灰的處理方法。 The most significant coal characteristics are:煤的重要特性是：Moisture content 水份

24、High heating value 熱溫度Grindability index 可磨系數(shù)Ash content 灰特性Ash fusion temperature 灰熔點的溫度Sulfur content 硫份These specific coal characteristics are far more meaningful in the design of the equipment and the station than is the rank of the coal being burned.煤的特性在對設備的設計和電廠的設計方面比煤的等級更加重要 Each specific co

25、al characteristic can affect the design of certain plant equipment and components. 煤的每種特性都會對專門的設備和部件都有影響As an example, consider the effect of the moisture on power plant components. 比如，煤的水分對電廠部件的影響 The general effect is to increase most boiler components sizes and to reduce boiler efficiency.總的影響是會增

26、加鍋爐部件的尺寸，而減小鍋爐的效率A high moisture content will require a larger air heater. 水分越高，越需要更大的空氣加熱器。This, in turn, requires an increase in the temperature of the inlet air to the pulverizers（粉碎機） since a greater volume of air is required to dry the coal in the pulverizer. 受此影響，需要增加進入粉碎機的空氣的溫度，因為需要更大體積的空氣來干燥

27、在粉碎機中的煤。This increases the initial primary air fan size and reduces the forced draft fan sizes. 這會增加一次風機的尺寸而減小從動風扇的尺寸。The burning of coal with a high moisture content results in a higher flue gas dew point, and raises the stack temperature needed to prevent corrosion. 燃煤含有高水分，會導致高流量的氣霧，而且會提高防腐蝕的溫度。T

28、he net result of a high-moisture-content coal is to reduce the overall power plant efficiency.高水分煤會減少整個電廠的效率，The high heating value of the coal is another property that significantly affects plant design. 煤的高位發(fā)熱值是影響電站設計的另外一個重要的特性The high heating value(HHV) establishes the rate at which coal is fed i

29、nto the furnace(firing rate). 高位發(fā)熱值確定煤被送入爐腔的頻率Since the HHV can vary from 19,000 kJ/kg to well over 28,500kJ/kg(12000 Btu/lb) and since the firing rate for a given furnace or boiler out put is inversely proportional to the HHV, it is easy to see that mass firing rates can vary by over 50%. 由于HHV的值會從

30、19000 kJ/kg變化到28,500kJ/kg，而且由于爐腔忽而鍋爐的燃燒頻率與HHV成反比，所以，燃燒頻率很容易改變50%。Thus the HHV will affect the design of the boiler combustion zone, burners, pulverizers, coal feeders, silo storage requirements, coal-handling equipment, and the size of the active and inactive coal storage.因此，HHV會影響到鍋爐的燃燒區(qū)域，燃燒器，磨煤機、送

31、煤機、筒倉儲備需求、輸煤設備的設計，以及煤儲存的動態(tài)與靜態(tài)。Air fan 風機Air heater 空氣預熱器Ash fusion temperature 灰熔點溫度Ash hopper 灰斗 Boiler 鍋爐Burner 燃燒器Coal ash 煤灰Coal feeder 給煤機Coal plant 燃煤電廠Coal-fired power plant 燃煤電廠Coal-handing equipment 輸煤設備Condensate pump 凝結水泵Combustion 燃燒Combustion technique 燃燒技術Condensate 燃燒區(qū)Condenser 凝汽器Con

32、tent 成分Convert 轉換Cooling tower 冷卻水塔Crush 破碎Cycle 循環(huán)Deaerate 除去空氣Dew 露Dew point 露點Draft 通風Drum 鍋筒，汽包Economizer 省煤器Efficiency 效率Electric generator 發(fā)電機Electrostatic 靜電的Electrostatic precipitator 靜電除塵器Embargo 禁止進出口，禁運Fan 風機Feed pump 給水泵Feed-water 給水Firing rate 燃燒率Flame 火焰Flue 煙道Flue gas 煙道氣Forced-draft

33、fan 送風機Fossil 化石的Fossil-fuel 礦物燃料Furnace 爐腔Fusion 熔化Generator 發(fā)電機Grindability 可磨性Grindability index 可磨系數(shù)Heater 加熱器HHV(High heating value ) 高位發(fā)熱氣Hopper 漏斗Index 系數(shù)Kilowatt 千瓦Kilowatt-hour 千瓦時Mechanical energy 機械能Mixture 混合物Moisture 濕度Moisture content 水分Multistage 多級的Nuclear 原子核Nuclear plant 核電站Precipi

34、tator 除塵器Preheat 預熱Pressure 壓力Primary air fan 一次風機Property 性能Pulverize 磨碎Pulverizer 磨煤機Pump 泵Rankine cycle 朗肯循環(huán)Raw 自然的Raw water 原水Reactor 反應堆Regenerative 回熱式，再生式Regenerative feed-water heater 回熱式給水加熱器Reheat 再熱Reheater 再熱器Reservoir 儲水池Reservoir water 庫容水Saturate 使飽和Saturate steam 飽和蒸汽Saturation 飽和狀態(tài)S

35、crub 清洗Separate 分離Silo 儲倉Slag 煤渣Stack 煙囪Steam 水蒸氣Steam drum 汽包Steam generator 蒸汽發(fā)生器Steam turbine 汽輪機Steam-water mixture 汽水混合物Sulfur 硫磺Sulfur content 硫分Superheat 過熱Superheated steam 過熱蒸汽Superheater 過熱器Tower 塔Turbine 葉輪機Vapor 氣Virtually 幾乎2.Fuel handling and preparation for burning 2.煤的輸送和預燃燒2.1 Coal

36、Handing Systems2.1 輸煤系統(tǒng)The coal-handing systems at a large modern power plant unload the coal, handle it in the yard, and prepare the coal for burning in the furnace. 大型電廠中的輸煤系統(tǒng)卸煤，輸煤到煤場，然后準備送入爐腔中進行燃燒。Figure 2.1 is a block diagram which shows the major steps in the coal handling operation at a power

37、plant.圖2.1所示意的是在發(fā)電廠中輸煤操作的主要步驟。Since most coal plants burn pulverized coal, this section focuses on the preparation of pulverized coal. 由于大部分電廠燃燒的是煤粉，這部分將集中用于煤粉的準備。Rail shipment of coal accounts for nearly three-fourths of the coal delivered to U.S. power plants.鐵路運輸占到了全美電廠輸煤總量的四分之三。 Shipments of 10,

38、000 tons or more are quickly unloaded by rapid-discharge bottom railroad cars. A 100-ton load of coal can be discharged from a hopper car in 20 seconds. 運量為1萬噸以上的煤能夠被迅速卸下，100噸的煤能夠在20秒內被卸下。 Some western surface-mined coal and some eastern coal from Pennsylvania, West Virginia, and Ohio is shipped by

39、barge.西部產的煤和東部的賓夕法尼亞，西弗吉尼亞，和俄亥俄所產的煤通過貨輪運輸。 Barge shipment of coal accounts for approximately 10% of the coat used by U.S utilities. 輪運費用接近占美國用電費用的10%The barges used to ship coal are generally not self-unloading, except for a few barges on the Great Lakes. 用來運煤的貨輪逐漸不能夠自我卸煤，除了在五大湖上的少數(shù)運煤船。The power pla

40、nt must therefore have its own equipment for unloading barge coal. 電廠就應當擁有自己的卸煤裝置A typical unloader consists of a tower housing a trolly boom with a clamshell bucket. 一個標準的卸船機包括裝有活動小車和大抓斗的高塔。The bucket swings over the barge to load and dumps the coal in hoppers on shore. 抓斗在貨輪上來回走動，抓取煤料，在岸上卸下 The re

41、mainder of the coal used by utilities is shipped by either truck or overland conveyer. 剩下的煤由卡車或者陸上傳輸工具進行運輸Overland conveyers are used where power plants are located near large mines. 當電廠和大型煤礦位置較近時，采用陸地傳輸工具。 Coal stored at a power plant may be placed in either active storage or reserve storage. 電廠的儲備

42、煤可以放在活動的煤倉或者是固定的煤倉The active storage supplies the normal power operation while the reserve storage pile is kept for emergencies and delays in regular shipment.活動煤儲備用于提供正常情況下的發(fā)電，而固定煤儲備主要應對一般的輸煤過程中的緊急事件和延遲現(xiàn)象。 Current utility practice is to keep large inactive reserves, up to 500,000 tons, to ensure a

43、reliable fuel supply for 60 to 90 days of plant operation.現(xiàn)在的固定儲煤可以存儲50萬噸煤，保證電廠能夠供應60到90天的電。 Since reserve storage piles are usually outdoors, frozen coal is a problem often faced by power plants in the north during the winter months. 由于固定儲煤是在室外堆放，因此對北方來說，冬天的凍煤現(xiàn)象是一個要處理的問題。Surface moisture on the coa

44、l causes the coal particles to freeze together. 煤表面的水氣導致煤粉凍結The difficulties caused depend on the coal particle size. 由煤粒的大小決定問題的難度。Large chunks of coal have weaker ice bonds than small fine particles because the surface-to-volume ratio is much lower.大塊的煤比小塊煤粉更容易凍結，因為接觸表面的比率更小。 Severe winter weather

45、 conditions can cause entire train loads or reserve stacks of coal to freeze together solid. 有幾種天氣因素會導致由鐵路運輸和固定儲備的煤會凍結成塊There are three methods of dealing with frozen coal: heat, mechanical devices, and freeze-control agents(FCAs). The heating operation is performed in an enclosed thawing shed that

46、is heated by steam, electric, or gas heaters. 有三種方法處理凍煤的問題：熱，機械裝置，解凍機構。加熱操作是在一個封閉的融化棚中進行，該棚由水蒸汽，電和氣進行加熱。This method is becoming increasing expensive. 這種方法的成本絕來越高Alternatively, mechanical devices can be used to shake, crush, or vibrate in order to break up the coal-ice mass.兩者相比，機械裝置可以搖、壓、震碎煤冰塊。 Free

47、ze-control agents act as antifreeze to weaken the crystalline structure of the ice bond. 解凍裝置能夠弱化冰的晶狀結構，The most widely use FCA is ethylene glycol.最常用的解凍裝置試劑就是乙烯基乙二醇。 It is applied at a few pints per to of coal when the coal is loaded into the car or silo. 當煤被運到車或倉庫時，它提供少量的品脫到煤中。 Ethylene glycol has

48、 proved highly successful as freeze-control agent. 乙烯乙二醇作為解凍劑獲得很高的成功率。Coal in active storage is generally kept under cover to protect it from moisture and freezing. 而處于傳動狀態(tài)的煤料則被覆蓋起來防止水分和冰凍，Large concrete bunkers immediately adjacent to the boiler plant are usually used. In some cases, both the activ

49、e and inactive storage is under cover. 在鍋爐室的旁邊會有大的煤倉。在一些情況下，運動狀態(tài)的煤和靜止儲藏的煤都是被覆蓋的。This is particularly true for western coal, much of which is subbituminous, as it tends to produce large quantities of small particles, known as fines. 對于西部的煤更是如此，由于大部分西部煤是亞煙煤，所以它可能產出大量的小顆粒狀物。With these coals, dust and m

50、oisture can become serious problems, making closed storage attractive. 使用這些煤，粉塵和水分將是嚴重的問題，使得封閉儲藏非常必要。Large concrete silos are often used for this purpose. The silos are normally kept under a slight negative pressure to minimize dust problems. 建造大煤倉就是出于這個目的。煤倉經常處于微量的負壓狀態(tài)。就是為了使得粉塵問題最小化。Handing Equipme

51、nt 輸送設備Very large quantities of coal are handled daily at modern stations.在現(xiàn)代電廠中每天都有大量的煤需要輸送 A 600-Mwe unit, at full power operation, handles and burns approximately 300 tons of coal per hour, or 7200 ton of coal per day. 一個600MW的機組，在全額工作狀態(tài)下， 要每小時輸送和燃燒300噸煤，或者是每天7200噸。Some of the coal delivery and r

52、eceiving systems must be designed to handle up to 4000 tons of coal per hour . 一些煤料輸送和接收系統(tǒng)，必須要設計成能夠輸送4000噸煤每小時。One of the major tasks is building the active and reserve “ stacks ” of coal. 一個重要的任務就是要建活動式和固定式的煤堆。Although there are a number of techniques and a wide variety of equipment that can be use

53、d to stack and reclaim coal, stacking conveyers are widely used. 盡管有大量的技術和各種設備用于堆取煤料，但是堆取料機很是應用很廣泛。A particularly useful device is the bucket wheel stacker/reclaimer, which is designed to perform both the stacking and reclaiming operation.一個非常有用的裝置就是滾輪式堆取料機，它被設計用來即可以堆料，又可以取料。 Such a device would typ

54、ically be used to build long triangular piles by taking coal from a conveyer running parallel to the pile. 這種裝置被經常用于從輸煤機上卸煤，堆出長三角形的煤堆，這要求輸煤機的走向與煤堆平行。When the pile of coal reaches a maximum height, the stacker moves a few feet and continues to build another pile. 當煤堆達到最大高度時，取料機移動一小段距離，繼續(xù)堆棧另一堆煤。Reclaiming is done by reversing the direction of the wheel and conveyer. 取煤通過改變車輪和傳送機的方向來實現(xiàn)。 Other types of in-plant handling systems are lowering wells, teles